An elevator system with an elevator car, a counterweight and a traction means, which connects the elevator car with the counterweight, is known from EP 0 619 263 A1. In that case the movement of the drive pulley is transmitted by way of the traction means to the elevator car and the counterweight. Also provided are tensioning means by way of which the elevator car is acted on against the force of the counterweight by a tensioning force. In the case of, in particular, high-rise elevator systems it is thereby possible to provide compensation for imbalance, which arises due to the weight of the traction means, at the drive pulley so that slip of the traction means at the drive pulley is prevented and the loading of a drive motor unit driving the drive pulley is reduced.
The elevator system known from EP 0 619 263 A1 has the disadvantage that in a state in which the counterweight rests in its end setting on a buffer a further raising of the elevator car is possible. Particularly in the case of elevator systems of very high construction the weight of the traction means, which engages the drive pulley from the side of the counterweight, can be sufficient to ensure the friction, which required for raising the elevator car, at the drive pulley. Since this represents a significant safety risk, the constructional height of known elevator systems is, for safe operation, limited.